The invention concerns a discharge valve for a blood pressure measuring device or the like wherein a valve casing the interior of which is in fluid communication with an inflatable cuff and a pressure measuring device (gauge) and an air outlet leading to a flat valve seat located on the exterior of the valve casing said air outlet is closed off by an elastic (rubber) annular valve washer which is disposed with its central hole slid over a stud-shaped guide member and which has a ring-shaped control element on its outer edge, said control element being used for removing, i.e., deflecting away, said washer from the valve seat.
One known discharge valve of this type shown in U.S. Pat. No. 4,116,217 has a pressure space located along the axis of the valve casing, to which the pressure gauge is connected in one axial direction, and in the other axial direction a rubber bulb pump is connected in the usual manner, via a check valve. The inflatable cuff is connected, for example, in ordinary manner via a rubber tube connected at the side of the valve casing. For application to blood pressure measurement for example, the pressure in the pressure space must be releasable via a discharge valve. For this purpose with the known device, connecting tubes, i.e., nipples, are connected to the pressure space at about a 45.degree. angle to the axis, and these tubes open out into ring-shaped grooves which are coaxial to the axis of the device. These grooves are located in a ring-shaped surface piece which, in other areas, serves as a valve seat, at which location it is covered by a rubber valve washer. The valve washer is pressed against the valve seat by a valve spring, which surrounds the stud-shaped guide piece and engages the rubber washer on the side of the washer which is away from the valve seat. The valve spring is helical in shape. The inner edge of the valve washer is pressed securely against the valve casing from both sides. The outer edge is furnished with a ring-shaped control element. By manipulating this control element the valve washer can be lifted off the valve seat, with local deformation of the valve spring. This furnishes a convenient means of finely controlling the release of compressed air, which results in the intended pressure reduction in the system.
This known discharge valve having this configuration is expensive to manufacture, however, because it requires a large number of parts, some of which are difficult to fabricate, e.g. drill holes which run at an angle to the axis and are therefore hard to make, and in particular, uses a standard valve spring.